Trimble Applanix: Delivering on the ‘Last Meter’

The demand for autonomy is accelerating across  industries, reshaping how systems are being developed and deployed. 

For UAVs, the push for precision is driven by emerging use cases, such as package delivery, medical transport and complex route navigation in urban environments, all of which require centimeter-level accuracy in positioning and landing. 

Importance of Correction Services 

Trimble is expanding its Centerpoint RTX positioning technology from agriculture and surveying applications into the rapidly growing autonomous markets of UAVs, robotics and vehicles. 

CenterPoint RTX is a global correction service that delivers centimeter-level positioning accuracy, engineered to ensure reliable and precise positioning anywhere around the world. 

RTX employs a fixed, stable datum to ensure consistent and reliable performance. The system supports all major satellite constellations and frequencies, offering users a robust and flexible positioning system. The service can be accessed through either L-band satellite signals or a standard internet connection, eliminating the need for local base stations and making high-precision positioning far more scalable and accessible.

This level of reliability is crucial for emerging applications such as drone delivery. 

“When you start talking about package delivery, operators need robust positioning,” explained Joe Hutton, director of inertial technology and airborne products at Trimble Applanix. “One reason is what we call ‘the last meter’ — drones need to be able to land or drop packages consistently within that final meter of their destination.” 

Hutton noted that precision requirements are becoming even more demanding. “It’s actually getting smaller than a meter now. You need that robust centimeter-level positioning to ensure the drone is in exactly the right spot for safe and accurate delivery.”

When asked about alternative positioning methods, Hutton explained why traditional RTK systems can fall short for these applications. “RTK has its traditional limitations,” he said. “You have to be within 20 km of a base station, you need to set up infrastructure, and then you face all kinds of datum issues between different base stations.”

This is where CenterPoint RTX offers a significant advantage. “You don’t get those problems with CenterPoint RTX because it’s a global correction service operating on a fixed reference datum that never changes,” Hutton explained. “If you use the same technology to survey your landing spot — say with a Trimble DA2 product using RTX — everything fits perfectly. It’s always going to be in the same datum.” He noted that this consistency has proven very popular with users because it eliminates the complex datum coordination issues inherent in RTK systems.

Beyond datum consistency, Hutton highlighted another critical consideration: signal robustness and jamming and spoofing. “While commercial drone applications typically operate outside conflict zones where intentional jamming occurs, operators still need protection against interference,” he said. “You can have radios causing jamming just inadvertently.”

Trimble’s OEM GNSS/INS systems for UAV navigation, such as Trimble PX-1, use aided inertial navigation system (INS) software that blends GPS positioning with inertial sensors using RTX corrections to offer robust position and orientation data — including precise roll, pitch and heading measurements — that can maintain accuracy even during short GNSS signal outages. 

The system provides inertial-based heading, which addresses another critical challenge in drone navigation. Traditional approaches rely on magnetometers for heading determination, but these are easily influenced by nearby metal structures and electromagnetic interference. In contrast, inertial-derived heading comes directly from the IMU itself, making it immune to magnetic disturbances and far more reliable in complex environments, making it suitable for drone delivery in busy urban environments.